Mustad,
If he doesn't have access to a 22lr to learn to shoot properly my suggestion would be to start there. Not for hunting whitetail of course but for proper shooting technique.
The whitetail rifle I would go with is a 243. Great for whitetail and he can enjoy shooting it all day at the range.
My daughter started at 12 years old two seasons ago. She started out with the 22 and then used a 30-30 for deer hunting. Although she got a deer her first time out with the 30-30 if i had to do it all over again we would have bought the 243 first (she has one now). She would have enjoyed the range sessions more as she does now with the 243 than she did with the 30-30

Good luck and have a great time out there hunting with the boy